1. The Field of the Invention
The present invention relates generally to window coverings and more particularly to window coverings including a transparent or translucent sheet to which is flexibly attached a plurality of rigidified parallel vanes.
2. Description of the Prior Art
Fabric window coverings are often preferred by consumers for a number of their features. Features most often considered desirable are the softer appearance relative to traditional venetian blinds, the uniform appearance which they provide a window and insulating properties associated with cellular fabric shades.
Cellular fabric shades offering these features are known in the art. For example, U.S. Pat. No. 4,450,027 to Colson discloses cellular window coverings which may be made of fabric or fill materials. In the process disclosed in the Colson patent, a flexible strip of material is folded into a continuous longitudinal tube and the longitudinal folds thus created are currently set by passing the tubing material around a heat setting wheel. Adhesive is applied along one side of the flattened tubular material which is subsequently stacked by winding onto a rack having flat surfaces. The winding in this manner presses the adhesive to the next layer wound onto the rack to form a bonded unitary stack of closed tubular cells. When the ends are cut from the rack, the stack may be expanded and the permanently set creases provide a neat and uniform outward appearance.
U.S. Pat. No. 4,732,630 to Schnebley discloses a modification to the Colson process described above. In the Schnebley patent, a hot melt adhesive is applied to one side of the tubular material. After the flat tubular strips have been stacked and cut, they are placed in an oven under pressure and the hot melted adhesive is activated to bond the layers together.
Both of the above patents disclose window coverings which exhibit the desirable features discussed to this point. However, window coverings of that type lack one feature which is often desired by consumers. That feature is the ability to control the amount of light admitted through the window covering, similar to a traditional venetian blind. There have been some attempts to provide a fabric window covering with the ability to control the amount of light entering the room.
U.S. Pat. No. 3,384,519 to Froget discloses one such attempt. The window covering disclosed therein consists of two cloth layers spaced apart by moveable, parallel and flexible fabric blades having each of their marginal edges heat welded to one of the moveable cloth layers. With this window covering, relative movement of the two cloth layers in opposite directions changes the angle of the blades and thus controls the amount of light admitted through the covering. A number of undesirable features of the Froget window covering derive from the fact that it is constructed utilizing a heat welding process. First, this limits the fabric which may be utilized to thermoplastic materials. Also, heat welding necessarily requires a melting of at least some of the fibers of the materials bonded, thus providing an uneven outer appearance along the heat weld and producing unwanted crimps or creases in the materials which can result in failure of the fabric fibers. Further, heat welding is a relatively slow process which may require six or more seconds to create a bond over an extended length. This is too slow for application in high volume commercial production processes. Other drawbacks of the Froget window covering are that heat welds are limited in strength and it is difficult to achieve uniformly straight heat welded points over an extended length. French Patent No. 1,364,674 also issued to Froget discloses a similar window covering with the same general limitations.
U.S. Pat. No. 2,865,446 to Cole discloses a window covering in which a long rectangular piece of fabric is doubled back upon itself and a plurality of pleated elements are placed between the folded over sheets. The pleated elements are an accordion pleated fabric which extends when the two sides of the folded over fabric are moved relative to one another in a direction perpendicular to the accordion pleats. Such a window covering does not provide a uniform appearance because the accordion pleated fabric located close to the top of the window covering does not expand to the same extent as the fabric closer to the bottom of the window covering. Also, it is very difficult to insure that such accordion pleated fabric returns to its desired position after each expansion.
French Patent No. 1,309,194 discloses a curtain with variable opacity. In this curtain, screen or mesh parallel sides are provided with tiltable braids therebetween. The braids are said to be attached at their edges to the sides. However, no means for attachment is specified. The drawings appear to indicate a hinge type attachment and the specification ends by stating that the difficulties of construction are substantial.
U.S. Pat. No. 4,535,828 issued to Brockhaus shows a window insulator wherein a sheet of insulating material having encapsulated bubbles is appropriately slit and folded upon itself to form pivotal vanes. The insulating material is of the type commonly used as a stuffer in packaging. The vanes are supported along one edge by the sheet of material from which they are formed and along an opposite edge by flexible strands.
A venetian blind type window covering is disclosed in U.S. Pat. No. 2,577,227 issued to Brent. The Brent window covering incorporates a pair of flexible straps which have been folded upon themselves at spaced locations to form supports or pockets for slats which are pivotal by movement of the straps. The free edge of each folded portion of the straps are supported by other similar strapping.
U.S. Pat. No. 4,309,472 to Gotting et al. discloses a window covering having vertically extending vanes which have been independently made from synthetic fabric that has been stiffened in a thermal process. The vanes are suspended from their upper ends and manipulated in a conventional manner.
Great Britain Patent No. 1,494,842 discloses a window covering wherein a thermoplastic film or the like is forced into a corrugated configuration and then heat sealed to form envelope strips into which are inserted metal foil or the like. Various modifications are disclosed in the patent with means being provided to support the free edges of the envelopes so that they can be selectively pivoted to open and close the window covering.
German Patent No. DE3525515A1 issued to Moser discloses another window covering formed from two sheets of material having parallel vanes therebetween. The vanes are formed by gathering one of the sheets and folding it upon itself at spaced locations. The sheets are sewn together along the folds to form pockets. Strips of material can be inserted into the pockets for added stiffness.
Another patent disclosing a window covering with parallel vanes disposed between parallel sheets is U.S. Pat. No. 1,937,342 issued to Higbie. The vanes in the Higbie covering are formed from loops gathered from both sheets and define pockets for the receipt of more rigid slats.
French Patent No. 1,465,261 to Mollard very broadly and sketchedly describes an ensemble that includes a transparent panel to which is flexibly attached a multiplicity of elements which are opaque. The elements are affixed along one edge to the transparent panel as by gluing, sewing, soldering, stapling, etc. Cords or bands are attached to the opposite edges of the elements to pivot them about their attachment to the transparent panel. The patent is not written in very much detail as to the elements themselves. The patent also discloses an alternative embodiment wherein the transparent panel is pleated and lined or otherwise coated with an opaque glue or band in place of the elements of the first-described embodiment.
U.S. Pat. No. 3,851,699 issued to Shapiro discloses a vertical louver type window drape wherein a continuous sheet of fabric material is interwoven with a plurality of relatively rigid vanes such that the vanes which are light impeding alternate with light transmitting sections of the fabric. One obvious drawback of a system of this type is that the vanes overlap the fabric requiring excessive fabric in order to fabricate the entire window covering. Further, the vanes or louvers are only attached to the fabric material along a top and bottom edge thereof, thereby inhibiting the control over the fabric material during operation of the window covering.
Window coverings of the afore-noted type, as mentioned previously, are desirable from several viewpoints. It has also been discovered that variations in this general type of window covering may be desirable from many standpoints, both utilitarian and aesthetic. It is to provide alternatives and improvements to the afore-described prior art systems that the present window covering has been developed.